Expermental Study On Mix Design And Mechanical Properties Of Recycled Concerte

Recycled concrete is a new type of material for the civil engineering.It is made from waste aggregate,clean and environmentally friendly,but also can reduce the excessive consumption of natural sand,reduce the environmental burden.Recycled concrete is a green building materials,with good development potential and prospects.However,due to the large differences in recycled aggregates,and many influential factors,so there is no special standards and norms to guide the construction.In this paper,a series of experimental studies have been carried out concerning the effects of different fine aggregate types,water-cement ratio,aggregate pre-wetting methods.The design of recycled concrete mix,the working performance of the mixture and the basic mechanical properties of the concrete are studied.Conclusions are as below:Mixing ratio: When the water-cement ratio of 0.6,the new natural sand recycled concrete appeared bleeding phenomenon,and work performance of sand recycled concrete,recycled sand recycled concrete and mixed sand recycled concrete is good;when the water is relatively small,through adding water-reducing agent to ensure the mobility of fresh concrete;aggregate pre-wetting or not on the regeneration of recycled sand concrete has little effect.Water-cement ratio: The mechanical properties of different types of fine aggregate recycled concrete are similar to those of ordinary concrete with the increase of water-cement ratio,which decreases with the increase of water-cement ratio.Natural sand recycled concrete and artificial sand recycled concrete are similar in the cube strength.Basic mechanical properties: Under the same conditions,the natural sand recycled concrete and artificial sand recycled concrete are better in compressive strength and elastic modulus.Mixed sand concrete and fully recycled concrete are better in axial compressive strength,and the natural sand concrete is better in the cracking strength.The strength of recycled concrete is similar to that of ordinary concrete,and the change of water-cement ratio is similar to that of ordinary concrete.With the increase of water-cement ratio,the strength of reclaimed sand recycled concrete is higher than that of water And the compressive strength of the recycled concrete prepared after the preheating of the recycled coarse aggregate is slightly lower than that of the recycled aggregate without the pre-wetting of the recycled aggregate.In addition,this paper collected a large number of recycled concrete literature data,through finishing analysis,fitting the natural sand recycled concrete mechanical properties of the formula and the relationship between them.It is aimed to provide a reference for the establishment of a unified renewable concrete specifications.